1. Field of the Invention
The present disclosure relates to an electrically commutated motor and a method for controlling said electrically commutated motor which comprises a plurality of stator phases and a rotor.
2. Discussion of the Background Art
Control and regulation of an electrically commutated motor require a rotary field control depending on the rotary field of the permanently excited rotor of the motor. Known control strategies are the single-phase control and the multiple-phase control which are alternatively employed in electrically commutated motors. In the single-phase control, the control deviation is determined merely in relation to a single stator phase, the so-called master phase, and the stator phase rotary field is controlled depending on the control deviation. The control is performed depending on a single phase, and consequently with a 360° resolution. In the event of rotational speed changes or major disturbances, the single phase control may possibly not ensure an adequate operational reliability due to its coarseness, in particular at low rotational speeds and under load.
Although multiple-phase controls, where the phase deviation of each stator phase is included in the control, are by far a more close-meshed control, a multiple-phase control may offer a poor or sometimes even inadequate control accuracy in the so-called stationary state, i.e. at constant rotational speed and relatively small loads, due to mechanical manufacturing tolerances which may cause phase asymmetries of the stator, for example, or due to an inaccurate sensor positioning. This phenomenon has in particular been found in digital, i.e. not continuously controlling, control systems.
The present disclosure provides an electrically commutating motor with an improved control, and an improved method for controlling an electrically commutated motor.